I run my test with Node v9.4.0 and everything pass without any problem, but runkit fail on

Error: Cannot find module 'ms’
Should we have ms?
We should have every package on npm. Sometimes this error is caused by a typo in your require path, but if you think we are actually missing this package, please confirm below and we’ll do our best to fix it as soon as possible!
Report ‘ms’ as missing
at Module._resolveFilename in core module.js — line 555
at Module._load in core module.js — line 482
at Module.require in core module.js — line 604
at require in core internal/module.js — line 11
in debug/src/debug.js — line 14
node.js startup…